A comprehensive diagnostic package based on immunohistochemical (IHC) and fluorescence in situ hybridization (FISH) techniques. The package primarily includes testing for CDK4 (Cyclin-Dependent Kinase 4) protein expression, an enzyme that regulates the cell cycle and whose expression is elevated in many high-grade liposarcomas, as well as essential complementary markers: MDM2 (a p53 repressor protein whose expression is increased with CDK4 in high-grade differentiated liposarcomas) and the S-100 marker (which may be positive in some liposarcomas). The main objective is to determine the co-expression of CDK4 and MDM2 proteins, which strongly suggests the presence of 12q13-15 amplification, a genetic feature characteristic of high-grade differentiated liposarcomas and atypical lipomas.